1. Technical Field
The invention relates to a resonator element, a method of manufacturing a resonator element, an oscillator, an electronic apparatus, a moving object, and a base station.
2. Related Art
It has been known that in the resonator device using a resonator element using a quartz crystal, due to the influence of a sub-vibration called spurious, the resonator element causes an abnormal oscillation at the time of startup. In particular in the case of the SC-cut resonator element capable of stabilizing the output frequency in a broad temperature range, the crystal impedance (CI)-value is high compared to the AT-cut resonator element used normally, and further, the CI-value further rises since the 3rd overtone is used, therefore it is difficult to oscillate the resonator element in the main vibration (C mode).
Further, in the case of the SC-cut resonator element, the spurious in the B mode is 1.09 times, and therefore exists in the vicinity of the main vibration, and the oscillation is caused using a B-mode suppressing filter. Therefore, it becomes difficult to oscillate, and the degree of influence of the B-mode spurious varies due to the CI-value variation, and the abnormal oscillation tends to occur. It should be noted that it has been known that the resonator element is made large in size in order to reduce the CI-value, but it has been difficult in practice to realize the large size under existing circumstance in which preference for miniaturization is strong.
In order to cope with the above, for example, JP-A-5-335877 (Document 1) discloses the fact that appearance of the spurious is suppressed by regulating the ratio between the thickness and the dimension in a predetermined axis direction (xx′ direction) of the quartz crystal.
However, in the ratio between the thickness and the dimension in the predetermined axis direction (xx′ direction) disclosed in Document 1, for the reason that it becomes necessary to decrease the electrode area, it is not achievable to sufficiently reduce the CI-value and the abnormal oscillation or the like occurs due to the influence of the spurious, therefore there is a possibility that the influence of the spurious cannot be avoided.